It is customary to replace heat exchanger tubes after they are no longer structurally sound, owing to corrosion or pitting, and when they commence leaking fluid. Pneumatically or hydraulically operated devices have replaced manpower to extract these tubes prior to making the necessary replacements.
In the past, devices have been developed to facilitate breaking the tube from the tube sheet that surrounds the tube. One such device is disclosed in U.S. Pat. No. 4,369,569, having the same assignee as the application herein. This tube-pulling device breaks the tube from the tube sheet by gripping the inner wall of the tube and then extracting the tube a short, specified distance. Because the device is unable to withdraw the tube entirely from the tube sheet, the user has to cut-off the standing portion of the tube and then reapply the device or use a completely different device to withdraw the remainder of the tube.
U.S. Pat. No. 3,857,158 discloses a tube-pulling device which utilizes a pair of pistons which move concurrently to effect removal of a tube. More particularly, after the pistons cooperate to pull the tube a relatively short distance, the tube is released so that the device can regrip the tube in preparation for the resumption of the tube-pulling operation. The disadvantage of this device is that it only pulls the tube a relatively short distance before the tube-pulling operation ceases, at least until the device can obtain a new grip on the tube in order to resume the tube-pulling operation. This intermittent and incremental pulling is done in short movements and is, therefore, very inefficient, as well as time consuming.